The present invention relates to a vapor reflow type soldering apparatus, and more particularly to an improvement of a unit for separating flux from heat medium.
Recently, electronic parts have been mounted onto a printed circuit board with higher density. These electronic parts include chip parts such as an IC having electrode terminals in four directions in a plane, i.e., a so-called flat pack IC, a resistor, capacitor and the like. The soldering operation for mounting the electronic parts onto the printed circuit board is a final step of the manufacture line and largely affects a performance of a final product. For this reason, it is considered that the soldering technique is the most important one in various steps of the manufacture line.
A vapor reflow type soldering apparatus, as a measure for performing the soldering operation in such a manufacture line is shown in, for example, U.S. Pat. Nos. 4,612,712, which is 4,658,513 and, which is 4,628,616 which was assigned to the present assignee. This apparatus is used for heating an article to be processed by passing the article through the vapor of a heat medium and utilizing the condensing latent heat of the heat medium. A material having a large specific weight relative to air under vapor state is used as the heat medium in order to make the temperature distribution of the vapor uniform and avoid undesirable excessive heating of the article to be processed.
The present inventors et al made certain proposals concerning the vapor reflow type soldering apparatus. More specifically, in U.S. Pat. No. 4,735,001 issued on Apr. 5, 1988, they propose a structure where heat is collected from returned heat medium after the heating of the article to be processed to thereby save a necessary heat quantity for evaporation and prevent faults of soldering due to the deficiency of the vapor. U.S. Pat. No. 4,776,105 issued on Oct. 11, 1988 shows the provision of a device for collecting the heat medium and a dividable conveyor. U.S. Pat. No. 4,809,443 issued on Mar. 7, 1989 shows the provision of a device for separating flux contained in the heat medium.
Also, copending U.S. patent application Ser. No. 385,160 filed on July 26, 1989 proposes a structure in which a position and a width of a vapor blowout port are variable in response to a change of a width of the article to be processed. Also, a copending U.S. patent application Ser. No. 07/425,025 filed on Oct. 23, 1989 and entitled "VAPOR REFLOW TYPE SOLDERING APPARATUS WITH IMPROVED COOLERS" proposes an improvement of coolers for collecting heat medium.
The vapor reflow type soldering apparatus shown in the above patents of the present inventors is provided with a tank which is filled with the heat medium vapor and a passage or path which is provided through the tank and through which the article to be processed is transferred. Coolers for collecting the vapor to prevent the escape thereof from the apparatus are provided on both sides of the passage close to the tank, respectively.
Furthermore, the apparatus shown in U.S. Pat. No. 4,735,001 is provided with a device for collecting the heat medium from the gas discharged from the apparatus. The heat medium collected by the coolers and the collecting device is returned back to the tank and is reused together with the heat medium which drops after having come in contact with the article to be processed. In order to keep well the performance of the heat medium to be reused, the apparatus shown in U.S. Pat. No. 4,809,443 is provided with a device for separating the flux from the liquefied heat medium collecting in a bottom portion of the tank.